1,721,024 research outputs found
A Mediterranean arbovirus: the Toscana virus
No full textToscana virus (Bunyaviridae family, Phlebovirus genus) is a sandfly fever virus responsible for human neurological infections. Sandfly viruses are transmitted by insect vectors (Phlebotomus species) and the infection is present in climatic areas that allow the life cycle of the vector. The arthropode-borne Toscana virus is the etiologic agent of meningitis, meningoencephalitis, and encephalitis. The frequency of this neuropathic infection increases in the summer months, peaking in August in the endemic Mediterranean areas (Italy, Portugal, Spain, and Cyprus). Infection diagnosis is carried out by molecular assays and immunoenzymatic tests, which are rapid and sensitive. Recent studies have investigated the antigenic properties of the viral proteins (nucleoprotein N and surface glycoproteins G1 and G2), to better understand their immunogentic role
Streptococcus gordonii as a live vaccine vector [Lo Streptococcus gordonii come vettore di vaccini ricombinanti]
No full textA host-vector system has been developed which enables the display of foreign antigens on the surface of the human commensal bacterium Streptococcus gordonii. Streptococcus gordonii expressing recombinant fusion proteins has been successfully employed in delivering heterologous antigens to the immune system, thus proving that it is a suitable candidate for a live vaccine vector
Simultaneous amplification of multiple human immunodeficiency virus type 1 DNA sequences from clinical specimens by using nested-primer polymerase chain reaction
No full textA sensitive and specific polymerase chain reaction (PCR) protocol with nested primers was developed for simultaneous amplification of three independent human immunodeficiency virus type 1 (HIV-1) DNA sequences from clinical specimens. DNA samples were first amplified with gag, pol, and env outer primer pairs and then with the corresponding three inner primer pairs in the same two-step reaction. Detection of the different amplification products was readily accomplished by simple agarose gel electrophoresis of the reaction product, even when starting with a single copy of HIV-1 DNA. Equivalent amounts of the three PCR products were generated, provided that the relative concentrations of the inner primer pairs were optimized. In addition, a beta-globin control primer pair could be conveniently included in the internal amplification step to verify that the DNA sample was suitable for PCR analysis. One nested multiplex PCR test was sufficient to detect HIV-1 DNA in all of 80 HIV-1-seropositive individuals and none of 50 HIV-1-seronegative healthy blood donors. The nested multiplex PCR procedure provides an attractive means for simple, rapid, and cost-effective direct detection of HIV-1 DNA in patient samples
Neutralization of Toscana virus is partially mediated by antibodies to the nucleocapsid protein
No full textThe envelope glycoproteins G1/G2 of Toscana virus (TOSV) seem to have the most important protective role in stimulating antibodies against the disease in humans, as well as antibodies against the Nucleoprotein (N), a partial neutralizing activity. Mice immunized with TOSV recombinant Nucleoprotein developed a strong humoral response to the TOSV that revealed the presence of neutralizing antibody than in vitro assay. The neutralizing antibody titre of mice immunized with the whole TOSV was analyzed before and after absorption of the sera with the recombinant N protein. A decrease of the neutralizing activity was observed in the treated sera. Similar results were obtained absorbing human anti-TOSV positive sera with the recombinant N protein. This study was designed to identify the nature of antibodies produced against the N protein of TOSV in mice and to establish correlation with antibodies produced in humans by natural infection. (C) 2001 Wiley-Liss, Inc
Immune responses to wild and vaccine rubella viruses after rubella vaccination
No full textAntibody responses to individual structural proteins (E1, E2, and C) of the M33 wild rubella virus and the RA 27/3 live attenuated rubella strain were assayed by immunoblotting in 11 girls, following immunization with RA 27/3 rubella vaccine. Serum samples were drawn before immunization and at 10 days, 1 month, 1 year, 2 years, and 3 years afterwards. All the subjects showed antibodies to E1 glycoprotein of both the virus strains up to three years after immunization, indicating the importance of E1 in immunity. Antibodies to E1 were always present when with neutralizing activity was observed. Antibodies to E2 protein of both the viruses and to the C protein of the M33 virus gradually disappeared with time in some samples, while antibodies to C protein of the RA 27/3 virus strain were found persistently in all the sera. © 1989 Springer-Verlag
Expression of recombinant E2 and C proteins of rubella virus in insect cells
No full textWe have constructed a recombinant baculovirus expressing the rubella virus E2 (42-45 KDa) and C (34 KDa) proteins. Sf9 cells infected with recombinant virus were able to synthesize and process the two proteins coded by a unique precursor gene. By immunoblot and immunoprecipitation analysis with polyclonal and monoclonal antibodies, a precursor polyprotein (66 KDa) and two other proteins migrating with an apparent molecular weight of 42 KDa and 36KDa were recognized as E2 glycoprotein and C protein, respectively. The recombinant E2 protein appeared to be glycosylated since it was susceptible to tunicamycin. The results indicate that the RV polyprotein coding for E2 and C is expressed and proteolytically cleaved in insect cells. This baculovirus expression system provides a useful alternative approach for the production of rubella virus antigens and should allow the purification of large quantities of the RV proteins for further biochemical and immunological studies
Detection of neurotropic viruses circulating in Tuscany: the incisive role of Toscana virus
No full textAdenoviruses (Ad) play an important role in the etiology of acute lower respiratory tract infections (ALRI) in young children in Chile. Our aim was to correlate the clinical severity of the infections with the Ad strains isolated during surveillance over 8 years. From 1988 through 1996, nasopharyngeal aspirates (NPA) were obtained for viral isolation and immunofluorescence assay (IFA) from children under 2 years of age hospitalized for ALRI; Ad isolates were further studied by restriction enzyme analysis of genomic DNA Of 3,097 cases enrolled, the Ad isolation rate was 12.6%. The most common admission diagnoses among Ad-positive cases were pneumonia and wheezing bronchitis (69.8%). Duration of Ad shedding was studied in 74 cases by IFA. Children excreting Ad for 4 or more days had a longer hospital stay than those shedding for 1-3 days (mean: 16.8 and 7.2 days, respectively; P< .01). Viral shedding for more than 3 days was associated with more severe outcomes. Genome typing of 221 out of 390 Ad isolates resulted in 87 subgenus C and 134 subgenus B strains, including 123 Ad genome type 7h (55.6%, P< .01). The IFA from the NPA was more sensitive for the detection of subgenus B (51.5%) than subgenus C infections (24.1%, P < .01). Children shedding Ad 7h had longer hospital stays (P < .01), a higher frequency of rectal temperatures over 39°C (P < .01), and greater need for additional oxygen (P< .02) than subgenus C cases. Four cases requiring mechanical ventilation were associated with Ad 7h infections. The data presented show that, in children hospitalized for ALRI, the genome type 7h was associated with a more severe clinical outcome
Comparison of M-MLV reverse transcriptase and Tth polymerase activity in RT-PCR of samples with low virus burden
No full textPossibility of reinfection after immunisation with RA27/3 live attenuated rubella virus
No full textA serological study was carried out on 527 girls immunized with RA 27/3 rubella vaccine. Data from all scheduled serum samples over a 5-year follow-up were available for 102 vaccinees, 10 (9.8%) of whom showed evidence of reinfection during the 5th year after immunisation, a year in which there was a rubella outbreak in the Siena area (Italy). We examined in greater detail the serological responses of these vaccinees after reinfection and the consequent implications pertinent to the duration of the protective immunity. © 1993 Springer-Verlag
- …
